Stamp Alphabet Series: U is For Uganda

Ultraviolet Lamp

An important tool used for the detection of luminescent tagging on stamps of the world, as well as for detecting fakes, forgeries, and alterations on stamps. UV lights are available in longwave, shortwave, or a combination of the two.

Underfranked

A cover that has an insufficient amount of postage affixed to it to prepay the service requested or implied. When they are detected, underfranked covers are assessed postage due.

Underinked Stamps

Sometimes known as dry prints, underinked stamps are caused by too little ink being applied to the plate during printing.

Underprints

A printing security device, underprinting is the application of a color, repetitive design, or patter, usually printed on the paper before a stamp design is printed. One form of security underprinting is burelage.

Ungummed

Any stamp without adhesive. This can include unused stamps that have lost their gum over the years but generally refers to those purposely issued without adhesive. In some cases, such as special printings or special souvenir sheets, stamps aren't gummed because postal use isn't anticipated. In other cases, such as early stamps printed for use in countries with high humidity, gumming isn't practical.

Unique

Only one copy of a stamp or other postal item is known. Not all unique stamps are tremendously valuable; their value is determined by demand. The supply of an only-known stamp is obviously limited, but if only one collector is interested, the stamp has much less value than one desired by two or more collectors.

Unpaid-Letter Stamps

The original name for postage due issues.

Untagged Error

A form of color-omitted error. An untagged error is a stamp that is supposed to have a phosphorescent coating but does not. There are several causes of untagged errors, including ink starvation, disengagement of the tagging rollers, and skipped areas of the web.

Unused

An uncanceled stamp. An unused stamp is generally assumed to have some or all gum, but may or may not, depending upon description. A mint stamp is expected to have full original gum.

Unwatermarked

Stamps printed on paper that does not contain watermarks. Some foreign stamps are printed on paper with large watermarks that do not cover the entire surface of a sheet or pane, leaving some stamps with a partial watermark and others with none. Used A postage, revenue, or special service stamp that has served its intended purpose. Most such stamps bear cancellations, cuts, punches, or other defacements to prevent reuse. Canceled-to-order stamps bear cancellations and are considered used, but they have not served postal duty.

Used Abroad

The stamps of any country, used and postmarked in any other country. This is sometimes done through special arrangement, and is sometimes done inappropriately. Used abroad covers are quite desirable.